DESCRIPTION: The principal investigator states that the biliproteins are a family of naturally occurring chromophores which are made up of linear tetrapyrrole derivatives covalently bonded to a protein (P) and that the most important member of this group is phytochrome (1), which functions as the "on-off" switch for photomorphogenesis in higher plants. He notes that photomorphogenesis can be divided conceptually into three stages: reception of light by means of a pigment(s), transduction of the light signal from pigment to gene, and the induction of development through genetic regulation and that in comparison to photosynthesis, where some aspects of the mechanism are known in considerable detail, relatively little is known about photomorphogenesis at the molecular level. It is reported that phytochrome (1) has been implicated in such light-dependent, irreversible processes as seed germination, flowering, and stem and leaf growth; as well as reversible modulations controlling leaflet and chloroplast movement, root tip adhesion, potassium uptake, and transmembrane potentials. The principal investigator states that research in this area is important, since at present we have little knowledge of how phytochrome (1) governs the growth, development and aging of plants. He notes that in part this is due to a lack of suitable model systems, as well as the extraordinary difficulties associated with the isolation and purification of the parent chromophore. In this proposal, he outlines synthetic studies which are to alleviate these difficulties. He notes that the methodology described is highly flexible (Method C), and allows for complete control over both relative and absolute stereochemistry, as well as regiochemical control across the backbone of the tetrapyrrole skeleton. It is indicated that flexibility of this type is important not only for the syntheses of 1, but also for the preparation of related porphyrins, corrins, and other biologically important tetrapyrroles.